The present invention relates to a method of growing single crystal of compound semiconductors having suppressed the generation of twin crystal from the shoulder portion of the single crystal to be pulled up and, in particular, relates to a method of growing single crystal of Inp not liable to generate the twin crystal.
Traditionally, in the growing method of single crystal of compound semiconductors by liquid encapsulated Czocharalski method (LEC method), as shown in FIG. 1, a heater (3) and a crucible (4) are installed in a hot zone (2) provided in a high-pressure chamber (1), an inert gas (9) is filled up inside the high pressure chamber (1), anti a melt (13) of raw material of compound semiconductor is retained in the crucible (4), the top surface of which is covered with a liquid encapsulant (12). A crucible shaft (7) is provided at the lower end of crucible (4) so that the crucible (4) can be rotated and, above the crucible (4), a rotatable pulling-up shaft (8) attached with a seed crystal (10) at the lower end thereof is provided. By pulling up the seed crystal (10) contacting with the top surface of melt (13) of raw material, the melt (13) of raw material is solidified gradually to grow a single crystal (11) on the seed crystal (10). Additionally, in the diagram, numeral (5) indicates a thermocouple and numeral (6) indicates an electrode.
Further, in order to grow the single crystal practically, the seed crystal having a particular planar orientation, for example, (001) orientation or (111) orientation is dipped into the surface of the melt of raw material and the seed crystal is grown while gradually cooling the melt, thus giving an improved a fixed shoulder angle to the growing crystal, as it is drawn up is better. By doing so, it is possible to grow the single crystal while suppressing the generation of twin crystal or poly crystal.
When pulling up the single crystal giving a fixed shoulder angle as described above, with materials having a small layer defect energy such as, for example, InP etc., the twin crystal is liable to generate from the shoulder portion thereof, leading to the difficulty in single-crystallization.